Space bar for play/pause
It has been discussed several times, MuseScore uses space bar to enter rests and so can't use it to play/pause.
Unfortunatly, it seems to be a popular request and an habit to use space bar to stop and start playback. All the major media player or score writers use space for this purpose including VLC, Spotify, Sibelius, iTunes but surprisingly not Finale (no shortcut?) or Noteworthy (F5 / F6). I open this feature request to gather opinions.